Today there is an increased need for very high quality glass sheets because of the development of flat display applications such as personal computer (PC) monitors, television (TV) monitors, personal digital assistants (PDAs) and other hand held devices, and perspectives for flat organic light emitting diode (OLED) displays and lighting technologies. In particular, there is an increased need today for very high quality glass sheets which are also flexible and have sufficiently small thicknesses (e.g., roughly below 150 μm thickness).
Some existing glass manufacturing systems and processes which use a fusion draw or a slot draw can produce glass sheets with such low thicknesses but they either have high production costs or do not yield sufficient surface quality. For instance, existing glass manufacturing systems which incorporate a slot draw produce inferior quality glass sheets with small thicknesses and also have high production costs. In contrast, the existing glass manufacturing systems which incorporate a fusion draw can produce very good quality glass sheets with small thicknesses but they have high production costs.
In addition, the existing glass manufacturing systems which incorporate the fusion draw and slot draw are limited to the production of glasses that do not devitrify easily. In particular, the fusion draw and the slot draw processes require the delivery of a molten glass which has a fairly high viscosity that is for instance greater than about 50,000 poises at the last point where the molten glass touches a non-moving body, like at a root of an isopipe in the fusion draw process or at an exit of a slot in the slot draw process. Unfortunately, there are a lot of glasses that do not meet this viscosity limitation so they can not be used to make thin glass sheets when utilizing the fusion draw process or the slot draw process. Accordingly, there has been and is a need to address the aforementioned shortcomings and other shortcomings associated making high quality thin glass sheets. These needs and other needs are satisfied by glass manufacturing system and method of the present invention.